This happened to me today on a major highway. The Ford garage told me it is a transmission problem. Check transmission problem solutions here in this blog. Solenoids, etc. It means your transmission is slipping, that happens in a lot of Mercury mystiques. not all true there is a throttle position sensor or T.P.S. on your throttlebody try that its way cheaper than transmission
the rpm is 5700
I have a 2001 mercury sable LS premium DOHC 24V engine and usually around 70 I'm at 2500-3000 RPM's
My 115 EFI mercury outboard would only generate 4200 RPM. The power gradually reduced and finally levelled off at 2400 RPM. I have had other problems in the past relating to power settings. Fuel injectors and impellor have been eliminated as potential causes.
what is wrong with my rpm it goes up and down
possibly bad distributer
Idle speed is set by the PCM and IS NOT ADJUSTABLE.
It is not so much the proper RPM but the difference in RPM between gears. If you up shift at 1800 and going in next gear you are at 1200, then you have a 600 RPM split between gears. So downshifting you would be around 1200 and would while floating gears or double clutching bring the RPM's up to 1800-1900. Many trucks have RPM range stckers on the visors my old Mack was 1050-1750, that's a 700 RPM range, I would down shift when I hit 1050-1150, at 1150 I would have to bring the RPM's up to about 1850 to get it to go into gear.
Sounds like the brushes are worn down in the alternator.
mass air flow sensor